Hey thegoodsirjames,
You've read it here before, and I think it is true: You will only love it so much, as long as you don't have to become totally depended of it. Especially if your kids are depending on making you generate income to provide them with a good life.
Since I have a kid, everything else doesn't matter to me anymore! In the evening hours I sometimes sit behind my pc making music and I really enjoy it. But I enjoy it even more to spend time with my daughter when she is awake. And I can only do so, because I have a day job (as a graphic designer), of which I can provide a decent living for my family and even gives me enough time to spend on my hobbies.
I know it sounds nice to be self providing, doing only the things you love, but this is only realistic for the few who pursue with full commitment. It doesn't sound like you're really committed to it (yet)!
Why I think you should not do it:
- You post this question on a forum. You are not sure yourself... Doesn't that tell you enough?!
- It's a very vague thing you want to do: "Something with ableton"!
- You've chosen other things than a music career in life already. Why didn't you chose it then? You are now 42 years old, and your story sounds like a typical mid-life crisis situation.
- ... and you have kids! (other people are depending on you now... It's not really the right time to start being "selfish")
If you still really think about pursuing your dream, and your loved ones support you all the way, then I think there are two ways to go about this.
1. Step by step
Keep your dayjob for now! There are a lot of things you can do to prepare yourself and your environment beforehand.
Have a solid plan. Not "doing something with Ableton". Come on! You can do better than that! You're 42 years old... You know how it works in the real world.
Think of it as setting up a business. After all, you want to generate income to provide yourself and your family from. Make a business plan! How are you going to earn money with Ableton?
After you've done that, you should do all the preparations for that and read up on it. Whatever you choose. Production. Do a course or get an education in Audio Engineering. Do some kind of internship in a studio. Set up a network. DJ-ing or performing artist. Get the stuff you need for that and learn from the best (Read books, Go to clubs, join a band, whatever)...
After all that, I think you can best take a sabbatical year (if this is possible in your company) since you already have saved some cash, and give it a go. I think a whole year should give you enough time to just be busy with what you would like to do and give you a good idea if it is worth continuing. If you see it is going in the right direction, you can always quit your dayjob.
... Otherwise you can at least say to yourself you gave it your best shot.
2. Head first
If you feel irresponsable

enough, just quit your dayjob and go for it.
However, this doesn't sound like you, because you haven't done it yet!
Whatever you decide... Good luck and just make sure you keep it real(-istic)!